Among the interactions of a generic multiorbital Anderson Hamiltonian for 3d impurities [1]},
we are neglecting the inter-orbital Hubbard repulsion \(U^{\prime } n_{1} n_{-1}\) , as this term is almost constant in the (particle-hole symmetric)
Kondo regime. We also neglect the pair hopping interaction \(J_{H} ({d}^\dagger _{1 \uparrow }{d}^\dagger _{1 \downarrow }{d}_{-1 \downarrow }{d}_{-1\uparrow } + {\rm H.c.})\) ,
as, for FePc on Au(111), the two-electron low energy sector contains only the triplet states due to the strong Hund's coupling [2]}.
While the inter-orbital Hubbard repulsion \(U^{\prime }\)  could be easily
included in the NRG computation, the pair hopping interaction breaks the separate conservation of the isospin in each channel \(\tau \) , resulting in a
very demanding computational effort.
